textproduct: Albany

WHAT HAS CHANGED

The Slight Risk (Level 2 of 5) for Thu-Thu night was moved slightly eastward to the Hudson River Valley. The Marginal Risk (Level 1 of 5) remains for locations north and east of the Hudson River Valley. Damaging winds remain the main threat with any severe thunderstorms.

Some changes to the PoPs and showers/thunderstorms timing with the highest probabilities in the mid afternoon into the early evening.

KEY MESSAGES

1) Isolated to scattered thunderstorms are expected to develop Thu afternoon and evening across the entire forecast area. Some could be severe with the greatest potential threat for damaging winds along with heavy downpours, which could result in isolated flash flooding.

2) Isolated to widely scattered showers and thunderstorms are possible on Friday with the cold frontal passage, as drier, less humid and seasonable weather is expected for the upcoming weekend.

DISCUSSION

KEY MESSAGE 1...

High pressure moves south and east of New England tonight with a mid and upper level trough approaching from the Great Lakes Region and southeast Canada. Low and mid level southwesterly flow will allow for some mid and high clouds to increase ahead of a warm front. Outside some patchy fog near Lake George and east of the southern Greens it will be a mainly dry night with lows in the 50s to lower 60s. The warm front will bring some showers and few thunderstorms in the morning, especially from the Capital District south and east. A weak mid-level short-wave interacting with the warm front will focus the showers/thunderstorms, as sfc dewpoints rise into the 60s. The latest HRRR runs have more shower/thunderstorm coverage in the morning/early afternoon compared to the 3-km NAM and some of the other CAMS.

Attention shifts to the potential severe weather threat, where SPC has locations along and west of the Hudson River Valley in a Slight Risk (Level 2 of 5), and the rest of the region in a Marginal Risk (Level 1 of 5). A prefrontal sfc trough will be gradually approaching from the west in the warm sector, as the warm front lifts north and west. The air mass becomes more humid with dewpoints in the mid 60s to close to 70F. The latest HREFs support mean SBCAPE values in the 1000-1750 J/kg range with slightly greater amounts with 0-6 km mean shear values of 25-35 KT. Multi-cells and isolated supercells will likely form into broken lines or clusters. DCAPE values approach 1000 J/kg but mid-level lapse rates are mainly 6C/km or lower. Some steepening of low-level lapse rates occur. Bowing segments, damaging straight-line winds or wet microbursts would be the main threat. Some clouds in the morning into the early pm may limit the severe threat early on. A clear slot may develop over central NY into locations west of the Hudson River Valley in the mid-pm, which may allow for some storm organization for a severe threat to occur (3-6 pm time frame). Some CAMs continue to vary on the timing of convection evolution and coverage. The strong to potentially severe storms may linger into the early evening until 7-10 pm before weakening. Isolated large hail will be possible, with any taller updrafts and due to the veering low-level wind profiles, which maybe backed slightly in height in the valley areas, an isolated tornado can not be ruled out. The HREFs shows modest mean fixed layer SigTor parameters of barely greater than 1 over parts of the region. Max temps look to be in the 70s to lower 80s.

PWATs increase to 1 to 2 STDEVs above normal across the forecast area in the muggy air mass. The PWATs will be in the 1.25-1.75" range with some slightly higher values close to the I-84 corridor. Some locally heavy rainfall is possible with the storms. Gridded hourly FFG values are 1.6-2.25" where the WPC Slight Risk (Level 2 of 4) is in place across the southeast Catskills, mid Hudson Valley into the southern Taconics and towards southwest New England. The mean low-level flow is about 25 KT. If any convection trains or back builds with high/intense flash flood rates, then an isolated flash flood can not be ruled out. The rest of the forecast area is in a Marginal Risk (Level 1 of 4). The dry antecedent conditions with the higher FFG values were reasons we did not issue a Flood Watch for flash flooding. Ponding of water or poor drainage flooding of urban and low-lying areas will be possible with the higher rainfall rates. The showers and thunderstorms will diminish south and east of the Capital Region shortly before or just after midnight with a muggy night with the cold front upstream with lows in the mid 50s to mid 60s.

KEY MESSAGE 2...

The cold front moves across the region in the late morning into the early to mid afternoon. Isolated to widely scattered thunderstorms will be possible south and east of the southern Adirondacks/west-central Mohawk Valley. Limited instability/shear should limit the potential for any severe threat and the timing of the front being early in the day. A drier air mass will begin to build into the forecast area from west to east in the afternoon into the early evening. Highs will range from the mid/upper 60s to mid 70s over the hills and mtns, and mid 70s to lower 80s in the valleys, as the west to northwest winds increase during the afternoon.

High pressure builds in Fri night into Saturday and will be in control through the weekend with a drier, cooler and less humid air mass. Lows will fall into the 40s to mid 50s Saturday morning and we stayed close to the NBM values. Max temps will be near normal Sat with 70s to around 80F for highs and will edge slightly above normal Sun and into early next week with lower to mid 80s in the valleys and upper 60s to mid 70s over the higher terrain. The next chance of showers and thunderstorms will be ahead of a cold front late Mon into Tue.

AVIATION /00Z THURSDAY THROUGH MONDAY/

Through 00z Friday...VFR conditions to start the period early this evening. However with just high level clouds overhead there could be some occasional fog developing at KGFL starting around 03z or 04z and lasting until around 08z when thicker mid level clouds move in. Later Thursday morning, there may be some SHRA developing into early afternoon, so will mention PROB30 at KALB/KPOU/KPSF. Then, scattered to numerous TSRA are expected to develop during the mid afternoon to early evening period at all TAF sites. However, there is low confidence in exact timing and placement, so will mention PROB30 for now. Details can be refined in subsequent TAF issuances. Any +TSRA could produce strong winds, downpours, and IFR vsby. Winds will be variable around 5 kt or less tonight, becoming southerly Thursday afternoon and increasing to 10-13 kt with gusts around 20-25 kt developing during the afternoon.

Outlook...

Thursday Night: Moderate Operational Impact. Chance of SHRA...TSRA. Friday: Low Operational Impact. Slight Chance of SHRA...TSRA. Friday Night to Sunday: No Operational Impact. NO SIG WX. Sunday Night: Low Operational Impact. Slight Chance of SHRA. Monday: Low Operational Impact. Slight Chance of SHRA...TSRA.

ALY WATCHES/WARNINGS/ADVISORIES

CT...None. NY...None. MA...None. VT...None.